1. Field of the Invention
The present invention generally relates to an illuminating apparatus for an image processing type measuring machine adapted to determine the size and shape of an object material on the basis of an image thereof obtained by an optical system, and more particularly to an illuminating apparatus for an image processing type measuring machine adapted to picture, in a striking contrast, not only an object having a stepped portion but also one without steps and instead having differently colored regions, for example, multicolored printed matter (printed patterns etc.), by varying the color of the light applied to the object.
2. Description of the Related Art
In an image processing type measuring machine adapted to optically image a portion of an object and determine the size and shape of the object on the basis of the image thus obtained, for example a microscope, a projector, or a three-dimensional image measuring machine, the illumination of the object to be measured plays an important role in obtaining an image of the object.
Besides a vertically downward illuminating system irradiating the object to be measured from substantially right above the object, a diagonal illuminating system irradiating the object in a direction inclined at a predetermined angle with respect to the axis of an optical system, and a system irradiating through the object to be measured from a position substantially under the object are known as illuminating apparatuses for image processing type measuring machines.
A halogen lamp (white light) has heretofore been used generally as a light source for these illuminating systems. However, when the illuminating light is white light, it is difficult in some cases to detect edges of the object due to the diversity of the objects to be measured. For example, where the object to be measured is a printed pattern, such as printed matter having a plurality of colors, the printed pattern does not have a stepped portion but rather only has different colors, so that the detection of edges of regions of different colors is difficult in some cases.
On the other hand, there is a case where an illuminating apparatus uses an LED (light-emitting diode) as a light source. Even with LED""s, however, the color is fundamentally limited, so that the problem of edge detection cannot always be solved. Moreover, the LED device itself is large. Therefore, even when LED""s of different colors are arranged with varied light applied to the object to be measured, non-uniformity of the color distribution is liable to occur, and the object to be measured cannot be pictured clearly.
When arranging a multiplicity of LED""s is difficult for space reasons, a problem with the brightness of illumination also arises in some cases.
The present invention has been made in view of these circumstances, and provides an illuminating apparatus for image processing type measuring machines capable of solving the above problems encountered in related art apparatuses of this kind. Machines incorporating an illuminating apparatus of the present invention cope with the diversity of objects to be measured, accurately obtain an image of the object to be measured, and rarely have problems with space limitations.
The illuminating apparatus for image processing type measuring machines according to the present invention that realizes the above features applies light to an object to be measured in order to determine the size and shape of the material on the basis of the image obtained by this irradiation operation. The apparatus includes a light source, a plurality of optical fibers, and a plurality of color filters. The optical fibers have incident ends, which are adapted to receive light that is sent out from the light source, and output ends, from which light is output toward the object to be measured. The optical fibers are divided at their incident ends into at least three groups. The plurality of color filters include red, green, and blue color filters inserted, respectively, between the incident ends of the optical fiber groups and the light source.
In such a structure, red, green and blue light is sent out from the optical fibers in each respective optical fiber group toward the object to be measured. Therefore, the color of the light applied to the object material can be changed to the desired color by changing the quantity of the light radiated from the light source into each optical fiber group. Accordingly, this illuminating apparatus can cope with the diversity of the objects to be measured, i.e., this apparatus can be applied to not only an object having a stepped portion but also to a material without a stepped portion but instead having differently colored regions. The apparatus makes it possible to accurately obtain images of these objects. Moreover, since the object and light source are connected by optical fibers they can be separated from each other and, thus, the apparatus rarely has design problems when there are space limitations.
In this structure, separate light sources are provided for each of the optical fiber groups and it is preferable that the respective light sources be formed so that the brightness of the light therefrom can be regulated. When the apparatus is formed in this manner, the light applied to the object material can be changed to any desired color by regulating the brightness of the light from the respective light sources provided to the optical fiber groups. Therefore, the changing of the colors can be done easily and with a simple structure.
It is preferable that the light output ends of the optical fibers be arranged annularly at an angle so that the optical axes of the optical fibers converge on one point. When the apparatus is formed in this manner, the portion of the object to be measured is irradiated with light from positions all around this portion and in a diagonal direction. This enables the boundary of regions of different colors in the object to be imaged accurately.
In this apparatus, the light output ends of the optical fibers can (a) be arranged in a ring with the color output from each fiber or each group of two or more adjacent fibers being different from that of neighboring ones, (b) be arranged in a ring divided into zones, with each zone outputting one color different from the other zones, (c) be arranged into concentric rings each outputting only one color, the fibers outputting one color all grouped into one ring.
When the structure (a) is employed, red, green and blue light is applied to the object to be measured from all along the ring of annularly arranged light output ends of the optical fibers since the optical fibers adapted to output the light of different colors are alternatingly arranged along a circle. Therefore, even when an obstacle exists in one direction, a shaded region does not occur on the object material. Accordingly, an illuminating operation without causing substantial non-uniformity of the color of an image of an object material can be attained.
When the structure (b) is employed, the arrangement of optical fibers along the circle can be carried out easily, and the cost of manufacturing the illuminating apparatus can be reduced since groups of optical fibers adapted to output the light of each color are all positioned in respective sections of the circle.
When the structure (c) is employed, illumination of an object at high brightness can be attained since groups of optical fibers adapted to output the light of different colors are arranged, respectively, in at least three rings in a concentric manner.
Another illuminating apparatus for image processing type measuring machines according to the present invention applies the light to the object to be measured, enabling determination of the size and shape of the object material on the basis of the object image obtained thereby. The apparatus includes a light source, a plurality of optical fibers receiving light from this light source from one of the ends of the fibers and output the light from their output ends toward the object, and a filter change-over unit inserted in a position between the light source and the ends of the optical fibers facing the light source. The filter change-over unit includes a plurality of color filters and is adapted to switch between different color filters.
When one of the colored filters is in front of the incident ends of the optical fibers with the filter change-over unit operated suitably in the illuminating apparatus having such a construction, the colored light corresponding to the color of the filter that is set is obtained. In this structure, a single light source serves the purpose, and, moreover, the optical fibers need not be divided into groups. This enables the illuminating apparatus to be manufactured easily at a low cost.